Fastening tool and fastening bolt

Abstract

In a fastening tool in which fastening members may be inclined as they are threadedly inserted together whereby almost no displacement load is applied to the members, a member having a bolt through hole with a tapered seat surface, and a fastening bolt that includes a bolt body provided about its outer periphery with a male thread, and a head provided on an end of the bolt body that has a diameter greater than that of the bolt body, in which the head has a lower outwardly curved tapered surface whose diameter is reduced toward the bolt body so that the lower surface abuts against the tapered seat surface when the fastening tool is used.

1. A fastening tool comprising: a fastening body which is provided at its central portion with a shaft hole for the insertion of a shaft, including a slot groove in its axial direction, and having at its one of opposed ends of the slot groove with a bolt through hole formed with a seat surface, and at the other end with a threaded hole, and
 a fastening bolt which is inserted into the bolt through hole of the one end in the fastening body and is threadedly engaged with the threaded hole of the other end to fasten the fastening body in the circumferential direction, wherein: 
 the seat surface of the bolt through hole in the fastening body is a conically tapered seat surface formed in a tapered groove, 
 the fastening bolt includes a rod-shaped bolt body provided at its outer periphery with a male thread, and a head which is provided on an end of the bolt body and which has a diameter greater than that of the bolt body and which abuts against the seat surface of the bolt through hole in the fastening body, and a lower surface of the head is formed into a convex arcuately tapered surface whose diameter is reduced toward a tip end of the bolt body, and, 
 wherein the arcuately tapered surface of said fastening bolt is an outwardly curved surface, and the fastening bolt is threadedly inserted into the fastening body whereby the outwardly curved surface of the arcuately tapered surface is in contact with the tapered surface of the fastening body. 
 
   
   
     2. The fastening tool according to  claim 1 , wherein the fastening body comprises a pair of divided pieces provided by two slot grooves disposed at locations separated away from each other through 180°,
 the fastening bolt comprises a pair of bolts for fastening the pair of divided pieces to each other in the circumferential direction. 
 
   
   
     3. A shaft coupling comprising:
 a fastening body having a central portion with a shaft hole for insertion of a shaft, including a slot groove in its axial direction, and which is provided at its one of opposed ends of the slot groove with a bolt through hole formed with a seat surface, and at the other end with a threaded hole; and 
 a fastening bolt which is inserted into the bolt through hole of the one end in the fastening body and is threadedly engaged with the threaded hole of the other end to fasten the fastening body in the circumferential direction; wherein: 
 a seat surface of the bolt through hole in the fastening body is a conically tapered seat surface formed in a tapered groove; 
 the fastening bolt including a rod-shaped bolt body provided at its outer periphery with a male thread, and a head which is provided on an end of the bolt body and which has a diameter greater than that of the bolt body and which abuts against the seat surface of the bolt through hole in the fastening body, and the head has a lower surface that is formed into a convex arcuately tapered surface whose diameter is reduced toward a tip end of the bolt body; and 
 two of said fastening bodies connected by an intermediate body are provided, one fastening body being disposed to receive a driving shaft, and the other fastening body being disposed to receive a follower shaft, so that the driving shaft and the follower shaft can be coupled, 
 wherein the arcuately tapered surface of the lower surface of said fastening bolt is an outwardly curved surface, and the fastening bolt is threadedly inserted into the fastening body whereby the outwardly curved surface of the arcuately tapered surface is in contact with the tapered surface of the fastening body. 
 
   
   
     4. The shaft coupling according to  claim 3 , wherein the fastening body comprises a pair of divided pieces provided by two slot grooves disposed at locations separated away from each other through 180°,
 the fastening bolt comprises a pair of bolts for fastening the pair of divided pieces to each other in the circumferential direction. 
 
   
   
     5. A shaft coupling comprising:
 a fastening body including a central portion, a slot groove in its axial direction that has opposed ends, a bolt through hole formed with a conically tapered seat surface in the form of a tapered groove at one end of the slot groove, and a threaded hole at the other end of said slot groove, and a shaft hole located in said central portion for receiving an inserted shaft; 
 a fastening bolt inserted into the bolt through hole in the one end in the fastening body and threadedly engaged with the threaded hole at the other end of the fastening body to thereby fasten the fastening body in the circumferential direction, said fastening bolt including a rod-shaped bolt body provided at its outer periphery with a male thread, and a head which is provided on an end of the bolt body and which has a diameter greater than that of the bolt body and which abuts against the seat surface of the bolt through hole in the fastening body, wherein the head has a lower surface that is formed into a convex outwardly arcuately tapered surface whose diameter is reduced toward a tip end of the bolt body; and 
 two of said fastening bodies connected by an intermediate body are provided, one fastening body being disposed to receive a driving shaft, and the other fastening body being disposed to receive a follower shaft, so that the driving shaft and the follower shaft can be coupled, and 
 wherein the bolt through hole and the threaded hole in the fastening body are arranged closer to the outer peripheral surface of the fastening body, and the fastening bolt is threadedly inserted into the fastening body whereby the outwardly curved surface of the arcuately tapered surface is in contact with the tapered surface of the fastening body. 
 
   
   
     6. The fastening tool according to  claim 1 , wherein a taper angle θ1 of the tapered curved surface of the fastening bolt is greater than a taper angle θ2 of the tapered seat surface formed in the tapered groove. 
   
   
     7. The fastening tool according to  claim 3 , wherein a taper angle θ1 of the tapered curved surface of the fastening bolt is greater than a taper angle θ2 of the tapered seat surface formed in the tapered groove.